An automated data acquisition system is under continuing development for the Vacuum Generators HB 501 ultrahigh-resolution dedicated scanning transmission electron microscope (STEM) to overcome the limitations of commercial systems for concurrent data acquisition and processing algorithms. As part of the system, a data acquisition and analysis program, Desk Top Spectrum Analyzer and X-Ray Database (DTSA), was developed for the Macintosh II class of Apple computers. This program has been modified to run in native mode on the Power PC series and on 68K Apple computers. Data acquisition is accomplished utilizing a specially modified, commercial, NuBus-compatible I/O processor and custom-designed acquisition and control software routines. A patent (U.S. Patent No. 5,299,138), held jointly by the NIH and the NIST, was issued for this analytical tool in March 1994. The DTSA is available for a modest fee from the Office of Standard Reference Data (OSRD), National Institute of Standards and Technology. A copyright has been also obtained by the OSRD.